﻿using System;
using System.Collections.Generic;
using System.Text;

public class StringCompute
{
    #region 私有变量
    /// <summary>
    /// 字符串1
    /// </summary>
    private char[] _ArrChar1;
    /// <summary>
    /// 字符串2
    /// </summary>
    private char[] _ArrChar2;
    /// <summary>
    /// 统计结果
    /// </summary>
    private Result _Result;
    /// <summary>
    /// 开始时间
    /// </summary>
    private DateTime _BeginTime;
    /// <summary>
    /// 结束时间
    /// </summary>
    private DateTime _EndTime;
    /// <summary>
    /// 计算次数
    /// </summary>
    private int _ComputeTimes;
    /// <summary>
    /// 算法矩阵
    /// </summary>
    private int[,] _Matrix;
    /// <summary>
    /// 矩阵列数
    /// </summary>
    private int _Column;
    /// <summary>
    /// 矩阵行数
    /// </summary>
    private int _Row;
    #endregion
    #region 属性
    public Result ComputeResult
    {
        get { return _Result; }
    }
    #endregion
    #region 构造函数
    public StringCompute(string str1, string str2)
    {
        this.StringComputeInit(str1, str2);
    }
    public StringCompute()
    {
    }
    #endregion
    #region 算法实现
    /// <summary>
    /// 初始化算法基本信息
    /// </summary>
    /// <param name="str1">字符串1</param>
    /// <param name="str2">字符串2</param>
    private void StringComputeInit(string str1, string str2)
    {
        _ArrChar1 = str1.ToCharArray();
        _ArrChar2 = str2.ToCharArray();
        _Result = new Result();
        _ComputeTimes = 0;
        _Row = _ArrChar1.Length + 1;
        _Column = _ArrChar2.Length + 1;
        _Matrix = new int[_Row, _Column];
    }
    /// <summary>
    /// 计算相似度
    /// </summary>
    public void Compute()
    {
        //开始时间
        _BeginTime = DateTime.Now;
        //初始化矩阵的第一行和第一列
        this.InitMatrix();
        int intCost = 0;
        for (int i = 1; i < _Row; i++)
        {
            for (int j = 1; j < _Column; j++)
            {
                if (_ArrChar1[i - 1] == _ArrChar2[j - 1])
                {
                    intCost = 0;
                }
                else
                {
                    intCost = 1;
                }
                //关键步骤，计算当前位置值为左边+1、上面+1、左上角+intCost中的最小值 
                //循环遍历到最后_Matrix[_Row - 1, _Column - 1]即为两个字符串的距离
                _Matrix[i, j] = this.Minimum(_Matrix[i - 1, j] + 1, _Matrix[i, j - 1] + 1, _Matrix[i - 1, j - 1] + intCost);
                _ComputeTimes++;
            }
        }
        //结束时间
        _EndTime = DateTime.Now;
        //相似率 移动次数小于最长的字符串长度的20%算同一题
        int intLength = _Row > _Column ? _Row : _Column;

        _Result.Rate = (1 - (decimal)_Matrix[_Row - 1, _Column - 1] / intLength);
        _Result.UseTime = (_EndTime - _BeginTime).ToString();
        _Result.ComputeTimes = _ComputeTimes.ToString();
        _Result.Difference = _Matrix[_Row - 1, _Column - 1];
    }


    /// <summary>
    /// 计算相似度（不记录比较时间）
    /// </summary>
    public void SpeedyCompute()
    {
        //开始时间
        //_BeginTime = DateTime.Now;
        //初始化矩阵的第一行和第一列
        this.InitMatrix();
        int intCost = 0;
        for (int i = 1; i < _Row; i++)
        {
            for (int j = 1; j < _Column; j++)
            {
                if (_ArrChar1[i - 1] == _ArrChar2[j - 1])
                {
                    intCost = 0;
                }
                else
                {
                    intCost = 1;
                }
                //关键步骤，计算当前位置值为左边+1、上面+1、左上角+intCost中的最小值 
                //循环遍历到最后_Matrix[_Row - 1, _Column - 1]即为两个字符串的距离
                _Matrix[i, j] = this.Minimum(_Matrix[i - 1, j] + 1, _Matrix[i, j - 1] + 1, _Matrix[i - 1, j - 1] + intCost);
                _ComputeTimes++;
            }
        }
        //结束时间
        //_EndTime = DateTime.Now;
        //相似率 移动次数小于最长的字符串长度的20%算同一题
        int intLength = _Row > _Column ? _Row : _Column;

        _Result.Rate = (1 - (decimal)_Matrix[_Row - 1, _Column - 1] / intLength);
        // _Result.UseTime = (_EndTime - _BeginTime).ToString();
        _Result.ComputeTimes = _ComputeTimes.ToString();
        _Result.Difference = _Matrix[_Row - 1, _Column - 1];
    }
    /// <summary>
    /// 计算相似度
    /// </summary>
    /// <param name="str1">字符串1</param>
    /// <param name="str2">字符串2</param>
    public void Compute(string str1, string str2)
    {
        this.StringComputeInit(str1, str2);
        this.Compute();
    }

    /// <summary>
    /// 计算相似度
    /// </summary>
    /// <param name="str1">字符串1</param>
    /// <param name="str2">字符串2</param>
    public void SpeedyCompute(string str1, string str2)
    {
        this.StringComputeInit(str1, str2);
        this.SpeedyCompute();
    }
    /// <summary>
    /// 初始化矩阵的第一行和第一列
    /// </summary>
    private void InitMatrix()
    {
        for (int i = 0; i < _Column; i++)
        {
            _Matrix[0, i] = i;
        }
        for (int i = 0; i < _Row; i++)
        {
            _Matrix[i, 0] = i;
        }
    }
    /// <summary>
    /// 取三个数中的最小值
    /// </summary>
    /// <param name="First"></param>
    /// <param name="Second"></param>
    /// <param name="Third"></param>
    /// <returns></returns>
    private int Minimum(int First, int Second, int Third)
    {
        int intMin = First;
        if (Second < intMin)
        {
            intMin = Second;
        }
        if (Third < intMin)
        {
            intMin = Third;
        }
        return intMin;
    }
    #endregion
}
/// <summary>
/// 计算结果
/// </summary>
public struct Result
{
    /// <summary>
    /// 相似度
    /// </summary>
    public decimal Rate;
    /// <summary>
    /// 对比次数
    /// </summary>
    public string ComputeTimes;
    /// <summary>
    /// 使用时间
    /// </summary>
    public string UseTime;
    /// <summary>
    /// 差异
    /// </summary>
    public int Difference;
}